8 Bits A/D with PIC16F877

[Jarle]

<font face="Courier New" size=-1>Hello!
Can anyone help me to tell me how I can set up PIC16F877 to a 8-bits A/D converter instead of 10-bits. I found this code but it doesn't work:
#device PIC16F877 *=16 ADC=10
use #device adc = 10 //to implement a 10-bit conversion,
// otherwise the default is 8-bits.

I have also only try: #device adc = 8
Default value is 10-bit.</font>
___________________________
This message was ported from CCS's old forum
Original Post ID: 14104

[PCM programmer]

:=<font face="Courier New" size=-1>Hello!
:=Can anyone help me to tell me how I can set up PIC16F877 to a 8-bits A/D converter instead of 10-bits. I found this code but it doesn't work:
:=#device PIC16F877 *=16 ADC=10
:=use #device adc = 10 //to implement a 10-bit conversion,
:= // otherwise the default is 8-bits.
:=
:=I have also only try: #device adc = 8
:=Default value is 10-bit.</font>
------------------------------------------------------

What version of the PCM compiler do you have ?
Some older versions had problems with the #device adc
statement. (You can see the version at the top of the
.LST file)

If you post the version, I can post a demo program
that shows how to get 8-bit adc output.
___________________________
This message was ported from CCS's old forum
Original Post ID: 14120

[Jarle]

Thank you for helping me!

My compiler version:
CCS PCM C Compiler, Version 2.717, 9459

cheers,
Jarle


:=:=<font face="Courier New" size=-1>Hello!
:=:=Can anyone help me to tell me how I can set up PIC16F877 to a 8-bits A/D converter instead of 10-bits. I found this code but it doesn't work:
:=:=#device PIC16F877 *=16 ADC=10
:=:=use #device adc = 10 //to implement a 10-bit conversion,
:=:= // otherwise the default is 8-bits.
:=:=
:=:=I have also only try: #device adc = 8
:=:=Default value is 10-bit.</font>
:=------------------------------------------------------
:=
:=What version of the PCM compiler do you have ?
:=Some older versions had problems with the #device adc
:=statement. (You can see the version at the top of the
:=.LST file)
:=
:=If you post the version, I can post a demo program
:=that shows how to get 8-bit adc output.
___________________________
This message was ported from CCS's old forum
Original Post ID: 14135

[PCM programmer]

:=What version of the PCM compiler do you have ?
:=Some older versions had problems with the #device adc
:=statement. (You can see the version at the top of the
:=.LST file)
:=
:=If you post the version, I can post a demo program
:=that shows how to get 8-bit adc output.

---------------------------------------------------------------
I got your private message. You should not rely on using
private messages, because they only work 1/3 of the time.
I have 21 messages listed as being sent to me, but I can
only see 7 of them. 14 of them are lost somewhere.
So I advise you to use the main board to post messages.

Your version of the compiler could have bugs with the #device
adc=8 statement. Here are two lines from the old CCS versions
page:
2.729 When using #DEVICE ADC=8 the correct 8 bits are now used for all chips
2.732 A Bug in #DEVICE ADC= is now fixed - See read.me file

So it's likely that you do have a problem with adc=8.
I made a demo program that should fix it. Just call the
new function "read_adc_8()", instead of calling read_adc().
I tested it, and it works OK.

<PRE>
#include "c:\Program Files\Picc\Devices\16F877.H"
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 8000000)
#use rs232(baud = 9600, xmit=PIN_C6, rcv = PIN_C7, ERRORS)
<BR>
// To use the read_adc_8() function, you need to include
// the following lines above main(). These definitions
// are for a 16F877.
#define AD_LEFT_JUSTIFY 0
#define AD_RIGHT_JUSTIFY 1
#bit ADFM_BIT = 0x9f.7
#bit ADC_GO_BIT = 0x1F.2
#byte ADRESH_REG = 0x1E
<BR>
char read_adc_8(void);
<BR>
//=====================================
void main()
{
char c;
<BR>
setup_port_a(ALL_ANALOG);
setup_adc(ADC_CLOCK_DIV_32);
set_adc_channel( 0 );
<BR>
while(1)
{
c = read_adc_8();
<BR>
printf("\%x\n\r", c);
<BR>
delay_ms(500);
}
<BR>
}
<BR>
//===============================
char read_adc_8(void)
{
ADFM_BIT = AD_LEFT_JUSTIFY;
ADC_GO_BIT = 1;
while(ADC_GO_BIT);
return(ADRESH_REG);
}
</PRE>
___________________________
This message was ported from CCS's old forum
Original Post ID: 14153